Elastomeric sheeting has been employed for many years in roofing applications as an alternative to tar and gravel roofs. Elastomeric sheeting is commercially available in single or multiple plys and is usually supplied in rolls which are unwound atop the roof to form individual, overlapping sheets. In order to secure the individual sheets to the roof, the overlapping edges of adjacent sheets are heat-welded or bonded together with adhesives, and fasteners are placed at intervals along the sheet which are connected to the roof.
One of the major concerns in the installation of elastomeric sheeting is to avoid leakage in the areas of attachment between the sheeting and roof. Nails, screws and similar fasteners which penetrate the elastomeric sheeting and extend into the roof were among the first types of fasteners employed to secure elastomeric sheeting to a roof. Although such fasteners may be effective in maintaining the elastomeric sheeting in place, there is always the danger of leakage at the point where the sheeting is penetrated particularly as the sheeting ages and is exposed to harsh wheather conditions.
Non-penetrating fasteners have been provided in the prior art to affix elastomeric sheeting to roof without the formation of holes or any other punctures therein. One type of non-penetrating fastener generally comprises a base plate fixedly secured to the roof having an upper surface over which the elastomeric sheeting is positioned. The upper surface of the base plate and facing surface of the elastomeric sheeting are then bonded together to affix the sheeting to the roof.
In some fasteners of this general type, as disclosed for example in U.S. Pat. No. 3,671,371, the base plate includes a metal or foil layer which is heated when exposed to a high frequency electric field and welds the upper layer of the base plate to the elastomeric sheeting. Other fastener designs of this type employ an adhesive material, such as hot melt adhesive, which is applied to the upper surface of the base plate and then heated with the elastomeric sheeting in position over the base plate to affect a bond therebetween.
One problem with fasteners relying solely on a weld or bond between the elastomeric sheeting and the upper surface of a base plate is the so-called "peeling" effect produced by the wind. As the wind blows across the elastomeric sheeting, uplift forces are produced which tend to pull or peel the elastomeric sheeting away from the base plate beneath. This is primarily due to the flexibility of the elastomeric sheeting which allows it to bend and flex in response to the uplift forces produced by the wind. Once an edge of the elastomeric sheeting begins to separate from the base plate, additional uplift forces from the wind tend to readily peel the reminder of the elastomeric sheeting away from the base plate resulting in complete failure of the fastener connection.